The Solar Wind

Rouillard, A. P.; Viall, N. M.; Pierrard, Viviane; Vocks, C.; Matteini, Lorenzo; Alexandrova, Olga; Higginson, A. K.; Lavraud, B.; Lavarra, M.; Wu, Yuling; Pinto, Rui; Бемпорад, А.; Sanchez-Diaz, Eduardo

doi:10.1002/9781119815600.ch1

Cited by 8 publications

(6 citation statements)

References 255 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The solar wind is commonly in the state of turbulence and serves as a natural laboratory of nearly collisionless magnetized turbulence (Bruno & Carbone 2013;Cranmer & Winebarger 2019;Verscharen et al 2019;Rouillard et al 2021). Magnetic fluctuations in the solar wind have a wide range of scales, including energy-containing, inertial, and kinetic scales.…”

Section: Introductionmentioning

confidence: 99%

Cross-scale Correlations in Imbalanced Solar Wind Turbulence: Parker Solar Probe Observations

Zhao

Meyrand

Feng

et al. 2022

ApJ

View full text Add to dashboard Cite

Based on Parker Solar Probe observations, this paper investigates the proton temperature, bulk speed, proton-scale magnetic helicity, and spectral index in the parameter space of (P I , σ c ), where P I is the magnetic energy density and σ c is the normalized cross helicity at proton inertial scales. Various correlations between these parameters are discussed and their relations are explored. These correlations indicate the following: (1) the turbulence with a larger P I is characterized by a higher σ c ; (2) a larger P I corresponds to a higher proton temperature, faster bulk speed, and steeper proton-scale magnetic spectrum; (3) a higher σ c accounts for higher proton-scale magnetic helicity. In particular, the P I has the largest correlation coefficient (CC) of 0.85 with proton temperature and has a considerably large CC of 0.70 with a proton-scale spectral index. The σ c has a moderate CC of 0.52 with magnetic helicity in the low β p case (β p < 0.6), where β p is the ratio of plasma to magnetic pressure. The correlation between σ c and P I is considerable with a CC exceeding 0.6 in the low β p case and tends to be negligible when β p approaches 1.5. These findings could be understood by the recently discovered “helicity barrier” effect and underline the importance of the generalized helicity invariant in low β p collisionless plasma for understanding imbalanced solar wind turbulence.

show abstract

Section: Introductionmentioning

confidence: 99%

Cross-scale Correlations in Imbalanced Solar Wind Turbulence: Parker Solar Probe Observations

Zhao

Meyrand

Feng

et al. 2022

ApJ

View full text Add to dashboard Cite

show abstract

“…Accordingly, such losses can be attributed to the disruption of the adiabatic particle motion due to distortion of the magnetic field, specifically by increase of the field line curvature. Such losses due to the magnetic field perturbation can happen even without significant SEP event, only due to geomagnetic storms that can be generated by other solar events not including energetic particles, like Corotating Interaction Regions (CIR) for instance (e.g., Rouillard et al., 2021 for a review). The maximum L of trapped protons, that is, the extension of the proton belt, can be related to the trapping limits estimated from magnetic field line curvature.…”

Section: Effects Of Sep and Geomagnetic Stormsmentioning

confidence: 99%

Proton Flux Variations During Solar Energetic Particle Events, Minimum and Maximum Solar Activity, and Splitting of the Proton Belt in the South Atlantic Anomaly

et al. 2023

View full text Add to dashboard Cite

The South Atlantic Anomaly (SAA) is an area where Earth's magnetic field is particularly low. This comes from the fact that the Earth's magnetic axis is tilted with respect to the Earth's rotation axis by an angle of approximately 11° and that the axis of the magnetic idealized dipole is located some 400 km away from the Earth's center (Brekke, 2013). As a consequence, the SAA is also a region where inner radiation belt particles can mirror at lower altitudes increasing the local particle flux.Unlike the geographic poles, Earth's magnetic poles are not fixed and tend to wander over time, and in parallel, the intensity of Earth's magnetic field is varying over time, for example, presently decreasing (Brekke, 2013). Hence the SAA has been drifting and growing in recent years (Amit et al., 2021;Anderson et al., 2018;Stassinopoulos et al., 2015), and those secular trends have an effect on the inner belt, especially as observed at Low Earth Orbit (LEO) (Girgis et al., 2021).In addition to secular drifts, the inner belt particles are affected by solar cycle variation. In fact, the low-altitude geomagnetically trapped population is known to be coupled to the atmospheric density through changes induced by solar activity (Anderson et al., 2018;Bruno et al., 2021b). Protons with energies above a few tens of MeV mostly originate through the Cosmic-Ray Albedo Neutron Decay (CRAND) mechanism. Because the CRAND source comes mostly from low geomagnetic latitudes due to high cutoff rigidities, the solar modulation of the cosmic rays has a relatively small effect on the variability of the trapped protons (Bruno et al., 2021b). The major variations are due to the atmospheric loss processes, including ionization and scattering of neutral and ionized atoms, induced by solar extreme ultraviolet (EUV) radiation heating the Earth's upper atmosphere. In fact, increased EUV during solar maxima leads to higher neutral and ionospheric densities, causing a decrease of proton fluxes concentrated at low altitudes and L shells.One of the particularities of the particle fluxes at low altitudes is that the high-energy trapped proton fluxes are strongly anisotropic, that is, the proton fluxes depend on their arrival direction in the plane perpendicular to the local magnetic field vector as well as on their pitch angle (angle between their velocity vector and

show abstract

“…The solar wind originates from the corona of the Sun. It streams outward and expands into the interplanetary space (Cranmer & Winebarger 2019;Rouillard et al 2021). The expansion has been shown to be nonadiabatic, indicating that a heating process must take place in the solar wind.…”

Section: Introductionmentioning

confidence: 99%

The Opposite Behaviors of Proton and Electron Temperatures in Relation to Solar Wind Magnetic Energy: Parker Solar Probe Observations

Zhao,

Feng,

et al. 2024

ApJ

View full text Add to dashboard Cite

Solar wind heating is an outstanding issue that has been discussed for decades. Research on the connection between solar wind particle temperatures and turbulence may provide insight into this issue. Based on Parker Solar Probe observations, this paper investigates the properties of solar wind proton and electron temperatures in relation to turbulent magnetic energy, via the calculation of correlation coefficients (CCs) between particle temperatures and magnetic energy. The calculations are regulated by the spatial scale, plasma beta (β), and the angle between the solar wind velocity and background magnetic field, where the plasma beta is the ratio of plasma thermal to magnetic pressure. Results show that the correlation between proton temperature and magnetic energy is positive and can be strong with a CC exceeding 0.8. The strong correlation preferentially occurs at ion scales, with the wind velocity and background magnetic field quasi-perpendicular and over a wide beta range (β < 3.0). On the other hand, the correlation between electron temperature and magnetic energy is commonly negative, often with an intermediate or negligible CC, accordingly. The CC with an amplitude up to 0.8 can arise at larger scales with the wind velocity and background magnetic field quasi-(anti)parallel and in the low-beta case (β < 0.6). The implication of these findings on the physics of turbulent heating in the solar wind is discussed.

show abstract

The Solar Wind

Cited by 8 publications

References 255 publications

Cross-scale Correlations in Imbalanced Solar Wind Turbulence: Parker Solar Probe Observations

Cross-scale Correlations in Imbalanced Solar Wind Turbulence: Parker Solar Probe Observations

Proton Flux Variations During Solar Energetic Particle Events, Minimum and Maximum Solar Activity, and Splitting of the Proton Belt in the South Atlantic Anomaly

The Opposite Behaviors of Proton and Electron Temperatures in Relation to Solar Wind Magnetic Energy: Parker Solar Probe Observations

Contact Info

Product

Resources

About